Alzheimer's Disease (AD), Diagnosis

There are many conditions that can impair thinking and memory. There is no one specific test or group of tests for diagnosing Alzheimer's. Instead, the disease is diagnosed by symptoms, tests of the neurologic system, and results from diagnostic tests. These tests help exclude other conditions that might cause similar symptoms. When caregivers do detailed testing of thinking and memory skills, it may take several hours to complete. These tests can help detect Alzheimer's and other dementias at an early stage.

Caregivers must make a diagnosis of "possible" or "probable" Alzheimer's disease.

The evaluation may include:

  • A complete medical history, including information about:

  • The patient's general health.

  • Past medical problems.

  • Any difficulties the person has carrying out daily activities.

  • Medical tests, such as tests of:

  • Blood.

  • Urine.

  • Spinal fluid.

These help the caregiver find other possible diseases causing the symptoms.

  • Neuropsychological tests to measure:

  • Memory.

  • Problem solving.

  • Attention.

  • Counting.

  • Language.

  • Brain scans allow the caregiver to look at a picture of the brain to see if anything does not look normal.

  • Information from the medical history and test results help the caregiver to rule out other possible causes of the patient's symptoms. For example, the following conditions can cause Alzheimer's-like symptoms:

  • Thyroid problems.

  • Drug reactions.


  • Brain tumors.

  • Blood vessel disease in the brain.

Some of these other conditions can be treated successfully.


The course the disease takes and how quickly changes happen vary from person to person. Lifespan of the disease depends on how old the patient is when diagnosed. But the disease can last for as many as 20 years.


An early, accurate diagnosis of AD helps patients and their families plan for the future. It gives them time to discuss care options while the patient can still take part in making decisions. Early diagnosis also offers the best chance to treat the symptoms of the disease.